During 11-12 July, INSIVUMEH reported 27 explosions from Santa María's Santiaguito lava dome complex based on seismic interpretation. Ash plumes from the explosions drifted SW. Explosions from Caliente dome on 13 July produced ash plumes that rose to altitudes of 4.3-5.3 km (14,100-17,400 ft) a.s.l. and drifted SW. Ashfall was reported from areas downwind. Incandescent avalanches of blocks from Caliente dome were observed.

Geological Summary. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing E towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)